參數(shù)資料
型號： M38000S7-XXXHP
廠商： Mitsubishi Electric Corporation
英文描述： 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
中文描述： 8位單片機
文件頁數(shù)： 126/173頁
文件大?。?/td> 4203K
代理商： M38000S7-XXXHP
3800 GROUP USER’S MANUAL
3-24
APPENDIX
3.4 Countermeasures against noise
3.4 Countermeasures against noise
Countermeasures against noise are described below. The following countermeasures are effective against noise in
theory, however, it is necessary not only to take measures as follows but to evaluate before actual use.
3.4.1 Shortest wiring length
The wiring on a printed circuit board can be as an antenna which feeds noise into the microcomputer.
The shorter the total wiring length (by mm unit), the less the possibility of noise insertion into a microcomputer.
(1) Wiring for the RESET pin
Make the length of wiring which is connected to the RESET pin as short as possible. Especially, connect a capacitor
across the RESET pin and the V
SS
pin with the shortest possible wiring (within 20mm).
Reason
The reset works to initialize a microcomputer.
The width of a pulse input into the RESET pin is determined by the timing necessary conditions. If noise having
a shorter pulse width than the standard is input to the RESET pin, the reset is released before the internal state
of the microcomputer is completely initialized. This may cause a program runaway.
Fig. 3.4.1 Wiring for the RESET pin
(2) Wiring for clock input/output pins
G
Make the length of wiring which is connected to clock I/O pins as short as possible.
G
Make the length of wiring (within 20mm) across the grounding lead of a capacitor which is connected to an
oscillatorand the V
SS
pin of a microcomputer as short as possible.
G
Separate the V
SS
pattern only for oscillation from other V
SS
patterns.
Reason
A microcomputer's operation synchronizes with a clock generated by the oscillator (circuit). If noise enters clock
I/O pins, clock waveforms may be deformed. This may cause a malfunction or program runaway.
Also, if a potential difference is caused by the noise between the V
SS
level of a microcomputer and the V
SS
level
of an oscillator, the correct clock will not be input in the microcomputer.
RESET
Reset
circuit
Noise
V
SS
V
SS
Reset
circuit
V
SS
RESET
V
SS
3800 group
3800 group
N.G.
O.K.
相關(guān)PDF資料
PDF描述
M38000S7-XXXSP 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
M38000S7-XXXSS 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
M38000S8-XXXFS 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
M38000S8-XXXHP 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
M38000S8-XXXSP 16 Characters x 2 Lines, 5x7 Dot Matrix Character and Cursor
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
M38000S7-XXXSP 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:8-BIT SINGLE-CHIP MICROCOMPUTER
M38000S7-XXXSS 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:8-BIT SINGLE-CHIP MICROCOMPUTER
M38000S8-DXXXSP 制造商:RENESAS 制造商全稱:Renesas Technology Corp 功能描述:8-BIT SINGLE-CHIP MICROCOMPUTER 740 FAMILY / 38000 SERIES
M38000S8-XXXFP 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:8-BIT SINGLE-CHIP MICROCOMPUTER
M38000S8-XXXFS 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:8-BIT SINGLE-CHIP MICROCOMPUTER
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